Background and purpose New prophylactics for migraine, targeting calcitonin gene-related peptide (CGRP), have recently emerged. Real-world data are important for a comprehensive understanding of... Show moreBackground and purpose New prophylactics for migraine, targeting calcitonin gene-related peptide (CGRP), have recently emerged. Real-world data are important for a comprehensive understanding of treatment response. We assessed the consistency of response to erenumab, a monoclonal CGRP receptor antibody, in a real-world setting, in order to determine which patients may be considered responders in clinical practice. Methods All erenumab-treated patients (n = 100) completed a time-locked daily electronic diary, and an automated algorithm was used to monitor treatment response. Monthly migraine days (MMD), non-migrainous headache days, days of acute medication use (MAMD), well-being and coping with pain were assessed for a 6-month period. The primary outcome was reduction in MMD compared to baseline. Results The numbers of MMD and MAMD decreased in all months, in both episodic and chronic migraine patients, compared to baseline (p < 0.001), while general well-being (p < 0.001) and coping with pain (p < 0.001) also improved. Of all patients, 36% had an MMD reduction of >= 50% in >= 3/6 months, and 6% had such a reduction in all 6 months. For a >= 30% MMD reduction, the figures were 60% and 24%, respectively. Almost 90% of patients with an average MMD reduction of >= 30% over the first 3 months had a sustained response in the last 3 months. In addition, 20% of patients without an initial response (average <30%), had a delayed response (average >= 30%) in the last 3 months. Conclusion Erenumab was effective in migraine patients who were highly refractory to previous prophylactics. As a practical guideline, we propose that treatment be continued for at least 6 months and that patients with a >= 30% MMD reduction in at least half of the treatment period should be considered to be responders. Show less